A British banker sentenced to life in prison for the gruesome slayings of two Indonesian women appeared in a Hong Kong court on Tuesday to appeal his conviction.

Lawyers for Rurik Jutting made their case in the semiautonomous Chinese city's Court of Appeal, arguing that the trial judge gave incorrect instructions to the jury on deciding their verdict.

The nine-person jury last year convicted Cambridge University-educated Jutting of the 2014 killings of Seneng Mujiasih, 26, and Sumarti Ningsih, 23.

The case shocked residents of Hong Kong, while also highlighting wide inequality and seedy aspects usually hidden below the surface.

Jutting, 32, watched the proceedings from the dock Tuesday, wearing a blue dress shirt and often leafing through a bundle of court documents as he followed along. During a break he chatted with the three uniformed court officers sitting alongside him.

Jutting worked for Bank of America-Merrill Lynch, while Seneng and Sumarti arrived in Hong Kong as foreign maids but ended up as sex workers. During the trial, jurors were shown graphic iPhone videos shot by Jutting of him torturing Sumarti and snorting cocaine.

Jutting attempted at the trial to plead guilty to manslaughter, which the court rejected. His defense argued that he was under diminished responsibility.

On Tuesday, lawyer Gerard McCoy told the three-judge appeal panel that the trial judge made a "fatal error" in his directions to the jurors on how to assess Jutting's psychiatric disorders and whether they constituted a mental abnormality.

Under Hong Kong law, an "abnormality of mind" that substantially impairs mental responsibility can be used as a defense against a murder conviction.